If you don't have the icon in your taskbar (Like myself, I get rid of anything that's unnecessarily cluttering my taskbars :p) right click on your desktop and select graphic properties, this is correct for windows Vista anyway.
If that brings up the intel graphics media box then all you need to do is click on the display settings tab and you should see the rotation options.
If you're using Windows XP or an earlier system it
may
be different, I have used Vista for the past few months so my knowledge of XP has diminished quite a bit :) I assume you can access a similar panel through right clicking on the desktop, properties and if my memory is correct, there should be some sort of settings tab in the display properties ;)
